Apparatus for furnace treatment of metal and metalliferous material



Dec. 1, 1931. D. H. MELOCHE 1,834,633

APPARATUS FOR FURNACE TREATMENT OF METAL AND METALLIFEROUS MATERIALOriginal Filed April 19, 1927 2 Sheets-Sheet 1 Swvemioz 1, 1931. n. H.MELOCHE APPARATUS FOR FURNACE TREATMENT OF METAL AND METALLIFEROUSMATERIAL Original Filed April 19, 1927 2 Sheets-Sheen;

Ewwawtoz N. Ma (/40 1 r y I y Patented Dec. 1 1931 *nrren STATES PATENTOFFICE,

I DANIEL H. MELOCHE, OF NEW YORK, N. ASSIGNOR 'IO AMERICAN RADIATORCOMPANY, OF NEW YORK; Y., A CORPORATION OF NEW JERSEY APPARATUSFORFURNACE TREATMENT OF METAL AND METALLIFEROUS MATERIAL Originalapplication filed April 19, 1927, Serial No. 185,041. Divided and thisapplication filed October 19,

1928. Serial No. 313,491.

This application is division of my ap- A plication Serial Number185,041, filed April 19, 1927, and entitled Method and apparatus forfurnace treatmentof metal and metal liferous material. v

My invention relates broadly and generally to new and usefulimprovements in furnace treatment of metal and metalliferous material,and more particularly contemplates a novel and eficient apparatus formelting or reducing metalliferous material.

The invention particularly contemplates a novel apparatus for use withfuel as oil, gas, or finely divided solid carbonaceous mate rial, whichburns in suspension in the combustion supporting atmosphere, and wasprimarily devised and is especially adapted for use with powdered coalor coke as the V 7 fuel. I am aware that it has been proposed tousefinely-divided coal admixed with a blast or stream of air to heatvarious types of metal treating furnaces, but so far as I am informed,these prior provisions have not proved practical in commercialapplication, because they were not capable of effecting a sufficientlycomplete combustion of the fuel under conditions permitting a propercontrol of the character (oxidizing, neutral 7 or reducing) of theheating gases coming into contact with the furnace charge of metal ormetalliferous material. In particular previous proposals for usingpowdered coal in melting metal have been open to the objection that themetal was thereby subjected to unthe objections heretofore stated andrender-f ing the firing of metal-treating furnaces with fine or powderedfuel'practicableand economical.

In the detailed description to be given hereinafter, a preferredembodiment of the invention is disclosed in connection with a furnace ofthe vertical cupola type employed for melting or reducing iron, such,for example, as pig or scraps, or mixture thereof, to molten or fluidform for use in foundry casting operations, but I wish it understoodthat my invention in its broad aspect is not to be limited to furnacesof the particular type shown and described, or for the melting andpurification of metal for the purpose stated, as it will be found usefulin the heat treatment of metal for other purposes as will be apparent tothose'skilled in the art from the following description.

The invention consists in the novel apparat'us,,t0 be more fullydescribed hereinafter, and the novelty of which will be particularlypointed out and distinctly claimed.

In the accompanying drawings I have shown, for purposes of example, oneform of furnace embodying my invention, and in connection with which mynovel method may be practised, in which drawings- Figure 1 is a view infront elevation, partly' in section, of a furnace embodying my1nvent1on;

Figure 2 is a top plan view-of the structure shown in Fig. 1, and

Fig. 3 is a detailed sectional view on the line 33 of Fig. 1. I

Referring to the said drawings by charactors of reference, 1 designatesgenerally a furnace of the vertical cupola type comprising a suitablecylindrical metal shell 2 lined with a refractory lining 3, andenclosing a charge receiving space 3".

The lining 3 may be of any of the commercial refractory materials usedin fur nace and cupola practice, or, the material may be a non-fusing,non-refractory material which will serve the purpose. The lining may beacid, neutral or basic, according to the reaction effect it is' desiredto produce in the furnace. In ordinary cupola practice where it isdesired to purify and melt pig iron or scrap, the lining nay be acid, inthe case of the reduction of metal-liferous material-+for example,ordinary iron oxide ores, the lining would be basic. The selection ofproper lining will be obvious to those skilled in the art, according tothe material to be treated and the effect and reaction it is desired toproduce. The cupola may be supported at its base upon any suitablefoundation structure 4:, and may be closed at the bottom with a suitabledrop bottom 5, ofany well known form. and the details of which need notbe shown or described as they are not necessary for a dis closure of myinvention. The furnace is also provided with the usual tap opening 6,through which the molten metal produced may be tapped, and with a slagspout 6 of any desired form. In-the present exemplification-the furnaceshown, contrary to the usual cupola practice, is preferably not providedwith blast tuyeres, or other air blast supply means for admitting air tothe charge-receiving space. At its base the furnace is provided with oneor more con1bus tion chambers 7, for example, four of such chambersbeing illustrated in the embodiment shown, and preferably being arrangedat equidistant point circumferentially of the furnace. Each of thesecombustion chambers comprises a shell 8, which may be rectangular incross-section, and which engages and is secured to the metallic shell ofthe cupola or furnace in an suitable manner, said shell, if desired,being jacketed, as at 9, to provide a surrounding space 10, to receiveair or other fluid cooling agent. The inner end of the shell 8 opensinto the cu pola through an orifice 11, which is located preferablyabove the bottom of the cupola, and said shell is lined, as at 12, witha; suitable refractory lining material. The outer end of the shell 8 isclosed by a suitable head 13 secured air and gas-tight to the shell 8'inany suitable manner, and the inner face of this head is also lined withsuitable ma.- terial. In the preferred embodiment the 1 externalcombustion chambers are arranged with their longitudinal axes inclinedupward from the point at which said chambers open into the cupola, but Ido not limit myself to this particular arrangement.

In the drawings, I have shown only so much of the cupola as is necessaryfor a clear understanding of my invention, the superstructure inclusiveof the charging inlet and appurtenances being omitted as the same may beof anywell known type, as will be obvious to those skilled in the artwithout illustration. Any suitable means may be provided for feedingpowdered coal or coke and air or other combustion supporting gases intothe combustion chamber in proportions and at rates insuring completionof combustion to the desiredextent within said chambers and the deliverytherefrom through the exit orifice or orifices of heating gases of thedesired oxidizing, reducing or neutral character. By complete combustionor combustion to the desired degree within the combustion chamber orchambers as these terms are used herein, I mean that the interaction orcombination in combustion of the carbon or other fuel constituents andthe oxygen in the combustion supporting atmosphere is completed withinsaid chamber or chambers so that no further combustion of the heatinggases due to theinteraction or combination of the constituents of saidgases occur after the latter leave said chambers. The emitted heatinggases contain free 0xygen when they are to have an oxidizing character,contain carbon monoxide or a mixture thereof with carbon dioxide whenthe emitted gases are to be of a reducing character, and contain neitheroxygen or carbon monoxide when the emitted gases are neutral incharacter, in such case the carbon of the fuel is all in the form ofcarbon dioxide.

In the preferred embodiment, the fuelfeeding means comprises an inletconduit 14- having its lower or outlet end 15 connected, as at 16, tothe central part of the head 13, and registering with an inlet duct 1?through the head and the lining thereof. The inlet duct 17 is,preferably located in line with the longitudinal axis of the combustionchamber so as to deliver a stream lengthwise of the chamber towardtheoutlet 11. Supported by the upperiend of the duct 14 is a casing member1 8, into which extends a fuel-feeding pipe or nozzle 19, fed from a,supply conduitQO, whichreceives a stream of the finely divided fuel andair from any suitable source (not shown). The chamber 18 is providedwith an outlet connection2l which is fed with secondary air imderpressure from a wind-box 22 surrounding the upper portion of thefurnace. The wind-box is supplied with air Lmder pressure impelled byany suitable blower or other impeller apparatus not shown. According tothe arrangement shown, the finely divided fuel impelled by an air streamis projected through the pipe ornoz'zle 19 into the chamber 18, andsecondary air from the wind-box 22 and under pressure, also passes intothe chamber 18 and the connection l i. The stream of air and fuel fromthe nozzle 19 mixes with. the air from the wind-box, passes through theconnection 15 into the external combustion chamber 7 in which the airand fuel mixture is ignited and burns. The combustion chamber 7 is ofsuch diameter and of such length from the fuel inlet 17 to the outletorifice 11 that the finely divided fuel will be suspended long enoughfor combustion which is substantially complete within the chamber to theextent permitted by the oxygen content of the combustion supporting gas,by the time it reaches said orifice.

Previously to igniting the fuel in'the combustion chamber 7, the cupolaor furnace may be provided with the usual sand bed 23, the. highestpoint of which is preferably just be;

low the lower edge of the orifice 11 and which slopes toward the taphole; Upon the sand bed is placed a bed of loose lump material The bed24 serves as a support for the charge,

as will'be hereinafter mentioned.

In the operation of the apparatus above described, the sand bed 23 isplaced in the fur-i nace and the bed 24 of coke or other intersticialmaterial, is placed upon the sand bed. The fuel supply through the duct20 and the secondary air from the WlIlCl-bOXQQ are then so regulatedrelatively as to produce combustion of the fuel in the furnace 7, and sothat heating gases of the desired characteristics will issue at theorifice 11. In cupola practice where metallic iron in the form of pig orscrap is to be melted for production of gray iron, the heating gaseswill be neutral at the orifice 11, or heating gases could be madereducing to the desired'extent to regailate the carbon content of theresulting melt.

. in case ofregulationproducin a neutral gas stream, a body or stream ofon, (carbon dioxide) will be projected from the orifice 11 into the bedof coke or broken material. The fuel in the chambers 7 may be'ignited byany of the usual means employed in starting combustion in cupolafurnaces, for example by.

placing a. suitable quantity of Wood on the sand bed, and kindllng thesame by an ignited wad of cotton waste soaked in Oll and tnrown in onthe wood through the charging inlet of the furnace before the charge ofcoke or other broken material is deposited in the furnace to form thesupporting bed. The coke or broken material 2% serves to support thecharge and to cause permeation and spreading. of the gas stream emittedfrom the orifice 11, so that the same will be evenly distributed acrossthe full area of the upper surface of the bed and the bottom area of thecharge. In the embodi-,

ment' described, the amount of fuel and air is regulated by any suitablecontrol for the fuel feed and the secondary air, so that it will beassured that substantially complete combustion of the coal occurs in thecombustion chamber, and substantially no unburned coal as such passesinto or through the bed 24-, or the gas stream may be made neutral orreducing. In the melting of ordinary iron for production of gray ironcastings, the stream emlttedfrom the orifice 11 at high temperature willbe substantially neutral or reducing, and the flow is continued untilthe interior of the charge-receiving space of the cupola'is renderednon-oxidizing. lVhen the preliminary burning of the fuel has beencarriedon long enough. tosecure the necessary heating of-the apparatusand to assure that the atmosphere or gaseous content within the cupolaor furnace is neutral or reducing as desiredthe metalliferous charge,for example, pig-iron, or scrap iron, in case the furnace be operated asa:.melting-cupo-la,is deposited in the space 3 through the usualcharging inlet, at thetop'of the furnace and descends torest upon thebed 24, the flow of hot gas from the combustion chamber being maintainedcontinuously so that the charge will be. melted to produce the desiredmolten product, which may be drawn off through the tap hole-6. a i

g It will be understood that in melting iron, where a neutral orreducing flame is employed, the bed 24if of coke, serves primarily as asupport for the metal charge and is not consumed during the operation,and there fore need only be replenished inorder-to make up formechanical losses, in which event additional quantities, when and ifrequired, may be supplied through the charging inlet of the furnace.

It will be noted that in operating my invention in connection with ironmelting, it is ordinarily importantto control the relative proportionsof: fuel and air-so as to insure substantially complete combustion inthe combustion chamber-7, and thereby produce a non-oxidizingflame orgas stream emitted from the orifice 11, so as to carry on the heating ormelting operation under conditions maintaining a neutral. or re'ducingatmosphere inthe charge-receivingchamber. This is effected in thepresentembodiment by control of the relative amounts of fuel and air, thelength and diameter of thefurnace chamber 7, and the'fact that thefurnace is substantially sealed against ingressof air, as

melting operation is taking place.

The means for furnishing finely divided carbonaceous solid fuel may beofany suitable commercial type available on the market and specificallyforms no part ofmy present invention. Such means (not shown) may consistof a grinding-apparatus for grinding or pulverizing the material anddelivering the same to an air impelling device or blower by which thefuel is blown or impelled in an air stream through the conduit 20 andbranches 20 to the nozzle 19. Any suitable type of blower or impeller(not shown) may be employed for drivingthe so-called secondary airnecessary for combustion to and through the wind-box 22, and thencethrough connections 21 to the chambers 18. Any suitable means may beemployed for regulating such, from any source while the reducing or the1 relative proportions. ofv air and fuel ejected from the nozzle 19, andthe proportion of secondary air necessaryto produce substantiallycomplete or desired combustion of the fuel in chamber 7 for example,itwill be understood this can be readily effectedby properly regulatingthe fuel feeding and air impelling means, or by valve in the sand pipes20*, or both. 7

By the term heating gas-es as employed herein, I mean the gaseous bodyor stream resulting from combustion of the fuel and combustionsupportinggas, whether such body or-stream be neutral, oxidizing, or reducing inits effect upon the metal or metalli-ferous charge. o

The invention has a number of advantages,

among which may be mentioned that sub-' stantially no slag isproduced'when the furnace is operated as a cupola to produce molten ironfor castings. The iron produced is substantially nitrogen free. Due tonon-oxidizetion of the original elements,the latter are held in theiroriginal condition, thus obviat-- ing metal losses and resulting inproduct of desired characteristics. The melting rate is also appreciablyincreased and the temperature of the metal at the spout o-r tap israised thus facilitating pouring. The method also reduces the so-calledsmoke losses, and produces; an appreciable saving in fuel.

Further advantages are that my new apparatus'obviat'es the necessity ofcharging fuel along with themetal charge into the furnace,

- and very much less fuel is consumed per unit of weight of metal meltedthan where the fuel is charged with the metal.

7 Due to the fact that littleor'no air except that employed to promotethe combustion of fuel in the combustion chamber is employed om meltingiron for gray iron castings, the

molten iron or other metal in the furnace is not chilled as it descendsthrough the bed, as is the case Where tuyeres or other means areemployed to admit an air blast to the charge.

This results in the metal not becoming oxidized, and also beingdelivered to the discharge spout at a. higher temperature than hitherto.1' p Another advantage is that due to the small amount, if any, of slagformed, there is practically no destructive chemical reaction on thefurnace lining, so that repair or replacement thereof from suchdeleterious reactions,

' is to a great extent obviated, thereby assuring continuous operationover long periods and saving the cost of such repair or replacement. j

While I have disclosed my invention as applicable for the melting ofiron in a furnace of the cupola type and'for such application describethe heating gases as being reducing or neutral, it is apparent'tha tbyproperly controlling the relative proportions'of fuel and air admittedto the external combustion chamber so as to employ an excess ofsecondaryair, I can produce oxidizing heating gases Where it-is desired toproduce an oxydizing effecton ametalliferous charge. By using reducingheating gases the apparatus and method can be readily employed for there duction of metalliferous ores. i

The apparatus described may be advantageouslyemployedin the heattreatment of metals for'productionof other products than gray cast iron,for example, they may be employed to melt steel in which case theheating gases would be regulated to be neutral, reducing or oxidizingaccording to the character of melt it is desired to obtain from theparticular metal to be melted. The invention can alsobe employed to meltiron for malleable castings in which event the heating gases wouldordinarily be oxidizing, and for melting non-ferrous metals inconnection with which reducing heating gases would ordinarily be used.

In addition to melting, the invention may also be used for smelting ironore, in which the heating gases would be highly reducing.

lVhat I claim and desire to secure by Letters Patent of the UnitedStates is 1. A cupola metal-melting furnace provided with a furnacechamber, an interstitial bed of non-combustible material at the bottomof said chamber and adapted to support a charge of metal a downwardinclined external combustion chamber communicating with'said chamber atits lower end through a port across which said bed extends, and meansfor supplying powdered coal and combustion supporting air in regulatedamounts to the upper end of said combustion chamber whereby combustionof said air and coal occurs within said second-named chamber such thatthe hot gases of combustion are 2. A furnace of the character describedhaving a charge-receiving chamber, a combustion chamber external to thereceiving chamber and having an outlet co1nmunicating with thecharge-receiving chamber, a fuel inlet discharging into said combustionchamber and longitudinally of said combustion chamber toward saidoutlet, a fuel supply duct communicating with said inlet, saidcombustion chamber being inclined clownwards from said inlet toward saidoutlet, means for supplying air to said duct, and means for feeding acombustible mixture of carbonaceous fuel and a combustion supporting gasto said duct.

3. furnace of the character described, comprising a charge-receivingchamber, a combustion chamber having an outlet dis charging into saidreceiving chamber, amixing chamber, a duct connecting said mixingchamber and said combustion chamber, a

conduit opening into said mixing chamber to supply fuel and a combustionsupporting gas thereto, and a second conduit opening into said mixingchamber to supplement the supply of combustion supporting gas from saidfirst-named conduit.

4. A furnace of the character described, comprising a substantiallyvertical shell hav ing a lining and enclosing a charge-receivingchamber, a second shell secured to said firstnamed shell and having alining and enclosing a combustion chamber, said chambers communicatingthrough an opening in said first-named shell and lining, saidcombustionchamber having an end wall provided with an inlet, a mixing chamber, aduct connecting said mixing chamber and said inlet, means to supply fueland a combustion supporting gas to said mixing chamber, and means tosupply additional combustion supporting gas to said mixing chamber.

5. A furnace of the character described, comprising a substantiallyvertical shell having a lining and defining a charge-receiving chamber,a second shell having a lining and secured in downwardly inclinedposition to said first-named shell, said second-named shell defining acombustion chamber opening at one end into said receiving chamber andhaving a wall closing its other end, said end wall having an aperturetherethrough, a duct secured to said end wall in line with saidaperture, a mixing chamber-communicating with said duct, a conduitopening into said mixing chamber for supplying finely dividedcarbonaceous fuel and a combustion supporting gas thereto, and a secondconduit opening into said mixing chamber to supply combustion supportinggas supplemental to that from said first-named conduit.

6. A furnace of the character described, comprising a substantiallyvertical shell having a lining and defining a charge-receiving chamber,a second shell having a lining and secured in downwardly inclinedposition to said first-named shell, said second-named shell defining acombustion chamber opening at one end into said receiving chamber andhaving a wall closing its other end, said end wall having an aperturetherethrough, a duct secured to said end wall in line with saidaperture, a mixing chamber communicating with said duct, a conduitopening into said mixing chamber for supplying finely dividedcarbonaceous fuel and a combustion supporting gas thereto, a wind boxextending around said first-named shell above said combustion chamber,and a second conduit opening from said box into said mixing chamber tosupply combustion supporting gas supplemental to that from saidfirstnamed conduit.

In testimony whereof I have hereunto signed my name.

55 DANIEL H. MELOOHE.

